The present invention relates to an information recording medium conveyer for conveying information recording media such as CDs (Compact Discs) or DVDs (Digital Versatile Discs) into or out of an information recording/reproducing device.
The present application claims priority from Japanese Application No. 2002-150682, the disclosure of which is incorporated herein by reference.
An information recording/reproducing device, such as a digital audio device, which utilizes CDs or DVDs (hereinafter collectively referred to simply as “discs”) is conventionally known which includes a conveyer having a so-called auto-loading function for automatically loading a disc into or unloading it out of the information recording/reproducing device.
For these conveyers, since such discs as having a variety of shapes according to their specifications have come into wide use, it is critical to select only those discs which, when loaded, are available to the information recording/reproducing device, and to prevent those discs unavailable thereto or foreign objects from being loaded therein.
More specifically, standard CDs and DVDs are classified into two types: one having an outer diameter (or a diameter) of about 12 cm (hereinafter referred to as the “large disc”) as shown in FIG. 12A and the other or a small disc having an outer diameter of about 8 cm as shown in FIG. 12B.
On the other hand, as shown in FIG. 12C, an additional annular member, called an adapter, has been developed which has an outer diameter of about 12 cm. The adapter is provided with a coupling portion having a circular hole at the center of the adapter to couple with a small disc. As shown in FIG. 12D, a small disc fitted into the coupling portion can serve as a quasi-disc (hereinafter referred to as the “adaptable disc”) which conforms to the specification for the large disc.
For use with an information recording/reproducing device to which available are those large discs and adaptable discs which conform to the specification described above, it is critical to employ such an information recording medium conveyer which ensures that these discs are selected and other foreign objects rejected. A known information recording medium conveyer of this type is configured as shown in FIG. 12E.
Referring to FIG. 12E, the information recording medium conveyer includes a conveying roller DRV for conveying discs by means of a rotational force, three optical sensors PD, MS1, and MS2 for detecting the passage of discs, and a microprocessor (not shown) for controlling the rotation of the conveying roller DRV in response to detection signals Sa, Sb, and Sc output from the respective optical sensors PD, MS1, and MS2, respectively.
The optical sensor PD outputs the detection signal Sa, which takes on a logic “H” upon detecting the disc face of a large disc or an adaptable disc and a logic “L” upon detecting a portion other than the disc face of a large disc or an adaptable disc (portions other than the large disc or the adaptable disc) or a portion in a clamping hole through which a light beam passes.
The optical sensors MS1 and MS2 output the detection signals Sb and Sc, which take on the logic “L” upon detecting the disc face of a large disc or an adaptable disc and the logic “H” upon detecting a portion other than the disc face of a large disc or an adaptable disc.
When a large disc DSC or an adaptable disc ADP is inserted through an insertion hole (not shown), the aforementioned microprocessor checks each of the detection signals Sa, Sb, and Sc output from the optical sensors PD, MS1, and MS2. While checking whether the detection signals Sa, Sb, and Sc have changed in accordance with a predetermined sequence, the microprocessor controls the rotation of the conveying roller DRV to load the disc into a tray TR provided at a so-called clamp position behind the conveying roller DRV.
FIGS. 13A to 13H show changes in the position of movement of the large disc DSC or an adaptable disc ADP with respect to the optical sensors PD, MS1, and MS2 and FIG. 13I shows corresponding changes in the level of the detection signals Sa, Sb, and Sc, the changes being provided when the disc DSC or ADP is loaded towards the tray TR.
As shown in FIG. 13A, when the disc DSC or ADP is inserted and then detected at its leading edge with the optical sensor PD, the conveying roller DRV is activated to rotate in the forward direction and start loading the disc DSC or ADP towards the tray TR.
The conveying roller DRV then exerts a rotational force on the disc DSC or ADP, which is in turn loaded as shown in FIGS. 13B to 13G. Accordingly, this causes the detection signals Sa, Sb, and Sc to change in accordance with the predetermined sequence shown by points in time t1 to t7 in FIG. 13I. In this case, the microprocessor determines the loading operation is carried out in accordance with a normal sequence, and thus allows the loading operation to continue so that the disc DSC or ADP is finally loaded into the tray TR as shown in FIG. 13H.
On the other hand, for the detection signals Sa, Sb, and Sc which have not changed in accordance with the predetermined sequence during the loading operation, the microprocessor recognizes the abnormal change in the course of the loading operation and determines that a foreign object has been inserted, thus allowing the conveying roller DRV to rotate in the reverse direction to thereby forcedly eject the foreign object through the insertion hole.
In addition to cases where a foreign object is inserted into the apparatus, a case where the source voltage supplied from a power source unit drops momentarily below its rating exists as an inevitable problem caused by the information recording/reproducing device or the information recording medium conveyer itself. However, the apparatus is provided with a function for preventing malfunctions and automatically restoring it to a proper loading operation even when such a power interruption has occurred.
More specifically, for an information recording/reproducing device mounted in an automobile, a power interruption may occur at the start of the engine while the information recording medium conveyer is loading a disc DSC or ADP, leading to degradation in reliability of the determination processing which has been performed by the aforementioned microprocessor immediately before the occurrence of the power interruption.
Even when such a power interruption has occurred, the microprocessor serves to automatically restore its reliability, thereby preventing unnecessary troubles.
FIGS. 14A to 14F show a restoring operation performed when a power interruption has occurred during the loading operation.
For example, as shown in FIG. 14A, suppose that a power interruption has occurred at a point in time ta while a disc is being loaded. In this case, the microprocessor causes the conveying roller DRV to rotate in the reverse direction to forcedly unload the disc being loaded towards the insertion hole as shown in FIG. 14B.
Then, as shown in FIG. 14C, when the trailing edge of the disc face of the disc being unloaded has passed by the optical sensors MS1 and MS2, the detection signals Sb and Sc invert from the logic “L” to the logic “H.” On the condition that the detection signals Sb and Sc have taken on the logic “H,” the microprocessor causes the conveying roller DRV to temporarily stop (at a point in time tc) and hold the disc, thereby preventing the disc from falling from the insertion hole.
Then, when the microprocessor determines that all the detection signals Sa, Sb, and Sc have taken on the logic “H” during the temporary stop or at the point in time tc in FIG. 14F, the process determines that the power interruption has been recovered and the process is then initialized in a predetermined manner.
That is, the detection signals Sa, Sb, and Sc all having the logic “H” (at the point in time tc) indicate that the same condition as that during the period from t1 to t2 in FIG. 13I has been obtained. This condition obtained allows the process to determine that the disc DSC or ADP has returned to a position at which the loading operation can be properly restarted and to be initialized to proceed to the normal loading operation.
After having been completely initialized, the process allows the conveying roller DRV to rotate in the forward direction to start the re-loading operation.
Starting and continuing the re-loading operation as such causes the detection signals Sa, Sb, and Sc to change at the point in time td in FIG. 14D in the same manner as at the point in time t2 in FIG. 13B. Continuing further the re-loading operation causes the detection signals Sa, Sb, and Sc to change at the point in time te in FIG. 14E in the same manner as at the point in time t3 in FIG. 13C.
Accordingly, when the detection signals Sa, Sb, and Sc change after the point in time td in FIG. 14F in the same sequence as the signals change after the point in time t2 in FIG. 13I, the microprocessor determines that the loading operation has been carried out in the normal sequence and then causes the disc DSC or ADP to be finally loaded into the tray TR.
Although not specifically described, suppose that a power interruption has occurred while the disc DSC or ADP placed in the tray TR is being unloaded. Even in this case, the same restoring processing as that performed when a power interruption occurs during the loading operation is carried out to eject from the insertion hole the disc DSC or ADP being unloaded.
As described above, the conventional information recording medium conveyer has the improved operability achieved by automatically loading or unloading an authorized disc and the improved reliability achieved by allowing the apparatus to automatically recover even from an inevitable power interruption and then continue the loading or unloading operation.
The aforementioned power interruption occurs unexpectedly and inevitably. However, there is a need for the development of a more reliable information recording medium conveyer which can prevent unnecessary troubles although inevitable.
In order to develop a more reliable information recording medium conveyer, the present inventor has studied in detail the contents of countermeasures which have been taken against power interruptions in the conventional information recording medium conveyer, and found the following problems.
A specific example of the problems to be solved will be explained below with reference to FIGS. 15A to 15C. First, as shown in FIG. 15A, suppose that a power interruption has occurred at a point in time during a loading operation, which has caused the conveying roller DRV to stop during its rotation and thereby caused the trailing edge of the disc face of the disc DSC or ADP to stay at the position of the conveying roller DRV (if there is not such a power interruption, the disc DSC or ADP will be loaded into the tray TR in the normal condition).
In other words, suppose that the power interruption has occurred when the disc face of the disc DSC or ADP has just passed by all the optical sensors PD, MS1, and MS2.
In this case, in the conventional information recording medium conveyer, the microprocessor allows the conveying roller DRV to rotate in the reverse direction to thereby initiate the unloading operation. Then, as shown in FIG. 15B, on the condition that the trailing edge of the disc face of the disc DSC or ADP being unloaded has passed by the optical sensors MS1, and MS2 and the detection signals Sb and Sc have taken on the logic “H,” the microprocessor causes the conveying roller DRV to temporarily stop rotating and the process to be initialized as described above.
However, in the situation shown in FIG. 15B, most part of the disc face of the disc DSC or ADP is found on the tray side with respect to the optical sensors PD, MS1, and MS2. This is clearly different from the situation shown in FIG. 14C in which most part of the disc face of the disc DSC or ADP is found on the insertion hole side with respect to the optical sensors PD, MS1, and MS2.
As described above, the disc DSC or ADP is located at a different position with respect to the optical sensors PD, MS1, and MS2. When the process is initialized as described above under this situation and the re-loading operation is initiated after the process has been initialized, it is not possible to obtain the same normal sequence as that after the point in time td (t2) in FIG. 14F.
For this reason, in the situation as shown in FIG. 15B, while even an authorized disc DSC or ADP is being actually reloaded, the microprocessor determines that a foreign object has been inserted and thus causes the conveying roller DRV to rotate in the reverse direction again, thereby starting to perform a forced eject operation.
When the forced eject operation is performed even on an authorized disc DSC or ADP as described above, the disc DSC or ADP is ejected from the insertion hole as shown in FIG. 15C, presumably resulting in a situation where the disc DSC or ADP is fallen from the information recording/reproducing device unless the user holds it.
In this context, as shown in FIGS. 14C and 15B, such a case is expected in which the disc DSC or ADP may be located at different positions with respect to the optical sensors PD, MS1, and MS2 (when initializing the process) depending on at which point in time of the loading operation a power interruption occurs. Accordingly, even with the disc DSC or ADP located at different positions, it is presumably necessary to ensure that the disc can be reloaded with high reliability.
FIGS. 15A to 15C show a problem to be solved with a power interruption which has occurred when the disc face of the disc DSC or ADP has just passed by all the optical sensors PD, MS1, and MS2 during the loading operation. On the other hand, where a power interruption has occurred when the disc face of the disc DSC or ADP has just passed by all the optical sensors PD, MS1, and MS2 during the unloading operation, it is presumably necessary to ensure that the disc can be unloaded with high reliability.